You sound like a bright young woman! I have never been in your shoes, but you sound like you have a very clear head on your shoulders! I commend you for making such an adult decision about whether to potentially end a child's life using logic and your own beliefs. No one your age should have to make such a decision!
I agree with whoever posted above that you should find a counselor to talk to. A school counselor or a religious leader would be a free option, and given the circumstances, you have no reason to be ashamed. If you feel any counselor is judging you, move on to a new counselor. I hope you find all the emotional support IRL but definitely use us ladies, too, as much as you want!
Rae (27), DH (26), Lucas (6/3/12), #2 due in December